An electrospray ion source method and system is provided for detecting emitter failure comprising a liquid chromatography column suitable for chromatographic separation of a sample. The column can have an inlet for receiving the sample; and an outlet for ejecting the sample. A make-up flow channel is provided for introducing make-up flow of liquid to the sample post-column, wherein the make-up flow normalizes the spray current. An electrospray ionization source is provided having one or more electrospray ionization emitter nozzles for receiving the make-up flow containing sample. A power supply can provide a voltage to the one or more emitter nozzles, and a measurement device can measure and monitor the spray current.